Several types of safety mechanisms are known: some safely devices are adapted to lock the trigger actuation lever assembly; other devices are adapted to place a rigid member in front of the striking mass; still others are adapted to extend the actuation spring.
A common type of safety mechanism, for example, is simply constituted by a safety pin which, in safety position, makes contact with a portion of the trigger in order to prevent any movement thereof, whereas in normal firing position it leaves the trigger free to perform its movements.
This type of safety device has the advantage of being extremely simple from the constructive point of view and of being adaptable to numerous and various firing mechanisms; however, in practice it cannot be used for example in firing mechanisms which provide an adjustment of the trigger, as occurs in target-shooting pistols.
UK Patent No. 213,805 discloses a self-loading pistol having a toggle link interposed between the hammer and the percussion spring. Depressible means operable by the act of gripping the pistol handle are provided to impart an initial movement of the toggle link from a safety position into a ready position. In one embodiment, the percussion spring is oscillable, being accomodated in a casing which is oscillably mounted in the handle.
Due to the complicated firing mechanisms and to the particular operating conditions, target-shooting pistols are normally not provided with a safety mechanism. Safety mechanisms, such as the one described above, would in fact interfere with the extremely sensitive operation of the trigger mechanism.
It is nonetheless advisable to provide a safety mechanism for this type of firearms as well, and this need is now even more strongly felt because of new regulations enforced by some countries.